Transient Simulation of DGI Engine Injector with Needle Movement

Meister, G.; Alajbegovic, Ales; Lai, Ming Chia; Yoo, Joon Ho

doi:10.4271/2002-01-2663

Cited by 10 publications

(3 citation statements)

References 5 publications

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“…Moving needle simulations that include a part of the injection chamber have also been performed. In [26] the injection chamber was modelled as full of liquid fuel, whilst in [27] an injection chamber full of air was used for the simulation of a pressure-swirl injector and in [28] a similar setup was used, in combination with VOF, to simulate the injection from a single-hole injector. It has been shown that the flow during the opening and closing stages of the needle's motion is transient, and hysteresis effects can take place [23] [25] [26].…”

Section: Introduction Backgroundmentioning

confidence: 99%

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Papadopoulos¹,

Aleiferis²

2015

SAE Int. J. Engines

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The design of a Diesel injector is a key factor in achieving higher engine efficiency. The injector's fuel atomisation characteristics are also critical for minimising toxic emissions such as unburnt Hydrocarbons (HC). However, when developing injection systems, the small dimensions of the nozzle render optical experimental investigations very challenging under realistic engine conditions. Therefore, Computational Fluid Dynamics (CFD) can be used instead. For the present work, transient, Volume Of Fluid (VOF), multiphase simulations of the flow inside and immediately downstream of a real-size multi-hole nozzle were performed, during and after the injection event with a small air chamber coupled to the injector downstream of the nozzle exit. A Reynolds Averaged Navier-Stokes (RANS) approach was used to account for turbulence. Grid dependency studies were performed with 200k-1.5M cells. Both k- and k- SST models were considered in the validation process, with the k- SST found to predict better the injector's flow rate. The cavitation models of Schnerr-Sauer and the Zwart-GerberBelamri were employed for validation against optical data of cavitation in a simplified nozzle geometry obtained from the literature. The Schnerr-Sauer model was in better agreement with the experiments, hence this model was subsequently employed for the real injector simulations. The motion of the injector needle was modeled by a dynamic grid methodology. An injection pressure of 400 bar was applied at the inlet of the injector. Two outlet pressures were examined, 60 bar and 1 bar. The results showed that the flow was far from steady-state during the injection event and that hysteresis existed between the needle opening and closing phases. This indicated the importance of transient simulations, contrary to widely-used steady state simulations at fixed needle lifts. The two outlet pressures resulted in very different final states of the flowfield in the nozzle. Specifically, the nozzle ended up either full of liquid fuel at the end of injection or full of air after most of the fuel had been ejected into the chamber downstream. These predictions highlighted phenomena that can increase HC emissions due to fuel leakage, as well as processes that may be linked to different formation mechanisms of nozzle deposits.

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Section: Introduction Backgroundmentioning

confidence: 99%

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Papadopoulos¹,

Aleiferis²

2015

SAE Int. J. Engines

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show abstract

“…Although CFD have often been used to describe single-phase injectors [13][14][15][16][17][18][19][20][21][22][23], application of CFD to the two-phase injectors under investigation introduces a number of novelties. Lagrangian flow computations and volume-of-fluid computations on this injector were performed in reference [8], providing interesting ideas for future modelling.…”

Section: Numerical Techniquesmentioning

confidence: 99%

Experimental and numerical study of a spark ignition engine with air-assisted direct injection

Boretti

Jin

Brear

et al. 2008

Proceedings of the Institution of Mechanical Engineers, Part D:

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An experimental and numerical study of the spray from an air-assisted fuel injector in a direct-injection spark ignition (DISI) engine is presented. The experiments are performed using ultraviolet laser diagnostics in a motoring optical engine that is a DISI variant of a production port-fuel-injected engine. Non-optical single-cylinder firing engine results of experiments and simulations are also presented. Recent related work by the present authors has shown that, under design conditions, the air-assisted injector exhibits strong coupling between the liquid and gas phases. It results in a filled-in conical spray of relatively fine atomization and low penetration, with liquid and vapour fuel concentrations close to the centrally located injector and spark plug, as required for lean stratified operation. This paper shows the strong effect of increasing the chamber temperature on spray evaporation and penetration. This observed temperature effect shows that spray evaporation should vary significantly during cold start. Exhaust gas recirculation (EGR) may also have a beneficial effect on DISI engine performance through enhanced spray evaporation, although this is difficult to verify experimentally. If true, this effect of EGR is a separate mechanism to the known beneficial effects of EGR in air-assisted DISI engines

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“…Moving needle simulations that included a part of the injection chamber have also been performed. In [41] the injection chamber was modelled as full of liquid fuel, whilst in [42,43] an injection chamber full of air was used for single-hole injectors. It has been shown that the flow during the opening and closing stages of the needle's motion leads to hysteresis effects [38,40,41].…”

Section: Introduction 1backgroundmentioning

confidence: 99%

Heat and mass transfer effects in the nozzle of a fuel injector from the start of needle lift to after the end of injection in the presence of fuel dribble and air entrainment

Aleiferis

Papadopoulos

2021

International Journal of Heat and Mass Transfer

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Transient Simulation of DGI Engine Injector with Needle Movement

Cited by 10 publications

References 5 publications

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Experimental and numerical study of a spark ignition engine with air-assisted direct injection

Heat and mass transfer effects in the nozzle of a fuel injector from the start of needle lift to after the end of injection in the presence of fuel dribble and air entrainment

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